Continuous distilling apparatus



Aug. 28, 1923.,

BAQSSZZE J. P. FOSTER ET AL CONTINUOUS DISTIL LING APPARATUS Fil -ed m.'1, 1921 4 Sheets-Sheet 1 Aug. 28, 1923.

J. P. FOSTER ET AL CONTINUOUS DISTILLING APPARATUS Filed; Aug, 1, 1921 4Sheets-Sheet 2 Aug. 2%, 1923 '-1 ,4ae.221"

J. P. FOSTER ET AL CONTINUOUS DISTILLING APPARATUS Filed Aug. 1, 1921 A4 Sheets-Sheet 5 F T TT T 1"" Aug 28, 1923.

J. P. FOSTER ET AL CONTINUOUS DISTILLING APPARATUS Filed Aug. 1, 1921 4Sheets-Sheet 4 Patent Aug. as, was.

JOHN PRESTON FOSTER AND'ALBERT F. zarsnnnn,

OF PAIA, TERRITORY OF EAWAII.

CONTINUOUS DISTILLING APPARATUS.

Application filed August 1, 1921. SerialNo. 489,142.

T 0 all whom it may concern:

Be it known that we, J on P. Fosrnn and Anenn'r F. MISENER, citizens ofthe United States, residing at Paia, Maui, Territory of Hawaii, haveinvented certain new and useful Improvements in Continuous DistillingApparatus; andfwe do hereby declare the following to be a full, clear,and exact description of the invention, such as will enable othersskilled in the art to which it appertains to make and use the same.

This invention relates to certain improvements in distilling apparatus,and particularly to a continuous still for the recovery of crude alcoholfor commercial purposes, such as motor alcohol, where it is necessary toproduce the highest possible amount of combustible of the highest proof.

The principal object of the invention is the provision of anapparatus ofthe character indicated which will be inexpensive to build and of suchsimple construction that the same may be readily assembled and set upwithout the assistance of experts, which is an important factor wheremotor alcohol is produced in more or less isolated localities, asubstantial portion of the apparatus being constructed of Wood, as t equality, odor, fiavor, etc., is of no importance whatever, the quantityand proof only being desired, and consequently an expensive copperfractionating still is entirely out of place and unnecessary in thisindustry.

The still of the present invention is of'that type in which thedistilling column comprises a series of chambers, through which theliquid and the vapor or gases flow in opposite directions for theseparation of the two, said chambers being provided with suitableopenings and connections for the purpose. One of the essential featuresof such a still is the bubbling floor provided 'for each chamber. Thisfloor has one or more capped openings, normally sealedby a liquid-levelmaintained in the chamber, through which and is deflected below theliquid-level. The vapor bubbling, through the fluid is freed from thefluid particles carried by. it into the liquid. The efliciency of thestill depends to a considerable extent upon the area of this bubblingfloor. \Vhen the liquid area is extensive, the vapor can spread out andtake a longer course through the liquid with the the vapor flowsupwardly consequent eater elimination of the liquid particles. hould theliquid area be circumscribed, the spreading of the vapor would berestricted and its travel through the liquid shortened, resulting in alessened elimination of the liquid particles.

, In stills of the type under consideration, in ordinary use thedistilling column is mounted in a perpendicular position. In

the present invention the distilling column is inclined at an anglebetween the perpendicuare horizontally positioned, thereby greatlyincreasing the area of the bubbling floors over What it would be withthe column pei7- 'pendicular, and without increasing the axial.cross-area or the volumetric capacity of the column. 'Also, by incliningthe distilling column, particularly so when a plurality of them is used,space is economized in the installation. The foregoing and otherfeatures of the invention will be described hereinafter more in detailand particularly defined in the appended claims.

The preferred embodiment of the inven- '65 'lar and horizontal,preferably about 30 With the column so tion is'illustrated in theaccompanying drawings, in which-- Fig. 1 illustrates the completeapparatus, partly in elevation and partly in section.

Fig. 2 is an enlarged detail view of a poztion of one of the similarlyinclined sections, illustrating the system of down-pipes for the liquidand. the vapor cap a range ment connecting each chamber.

Fig. 3 is a view, partly in elevation and partlyin section, on line 33of Fig. 2.

Fig. is a view,-partly in plan and partly in section, of one of thechambers.

Figs. 5 and 6 are views, partly in elevation and partly in section, onlines 5-5 and 6-6 of Fig. 1, and

Fig. 7 is a view in end elevation illustratimproved distilling apparatuscomprises substantially five sections, to wit: A, B, C, Y

D and E; section A representing the condenser, B the doubler, C and Dthe distilling columns proper, and E the heater for thealcohol-contalning substance to be treated, which section we have termedthe beer heater,

- therein a series of tubes ncaaeei all of said sections being arranged"in succession from the top to the bottom oi the apparatus, in the ordernamed.

The condenser A. is directly above the doubler B, and as illustrated,said condenser and doubler comprise roughs or housings 1 and 2 havingmounted 3 and 4 respectively, the said tubes being slightly inclined.The tubes 3 are connected at their ends by header motions 5 and 6, andthe tubes 4 of the doubler B are similarly connected by header sections7 and 8. The header sections 5 and 6 of the condenser A are mountedwithin the housing 1 on cross-partitions 9 and 10, and the headersections 7 and 8 of the doubler B are similarly positioned bycross-partitions 11 and 12. These sei' s of tubes fl-and 4 of thecondenser A and doubler B, respectively, are also supported byintermediate partitions 13 and 14. Upon referring toth'c drawings itwill be noted that the end partitions 9 and. 11, supporting the elevatedends of the tubes 3 and 4, are provided with openings 9 and-11 to permitthe passage of the cooling fluid admitted within the housings 1 and 2 ofthe condenser and doubler for the purpose to be hereinafter fullydescribed. In this same connection itwill be noted that the. partitions13 allow for the fluid passing over the top thereof and that thepartitions 14 are somewhat similarly constructed to the partitions Sland1l,to permit the cooling fluid to How beneath said partitions. Thecrosspartitions 10 and 12, supporting the header sections 6 and 8 of thedepressed'ends of the tubes 3 and 4, do not extend to the top edge ofthe troughs or housings 1 and 2, in order to permit the cooling oversaid partitions 10 and 12. .lVith this construction of cross-partitions,it will be noted that as the cooling lluid first enters the -(-ondenserA, by the pipe 15, it will be caused to flow under the partition 9, overthe partition 13, under the partitionld, and over the lower endpartition -10, thereby causing a continuous circulation of the fluidaround and through the tubes'il. The fluid will continue to rise intrough 1 until it reaches the level of the pipe 16, whereupon it willpass through pipe 16 into the botton portion of the trough 2, housingthe doubler B, whereupon said'fluid will be conducted through saiddoubler B in a manner similar to'its course through the condenser A.'lhe'lluid will continue to flow into the trough 2 of the doubler l3until it reaches the level of pipe 17 after which said fluid will beconducted over to the wasteby pipe 17 or by way of the by-passlS througha regulating valve 18 into the upper end of distilling column 1!) ofsection C of the apparatus.

The upper end of the distilling column 19 as also in communication withthe lower end at the tubes 4 of the doubler B by way of a preferablyarranged fluid to pass up and.

series of pipes 20, the upper end of the tubes' 4 of said doubler beingalso in communication, by way of a series of pipes 21, with For thesuite of convenience and clearness of description, it will be here notedthat in starting. the apparatus, the cooling fluid in the condenser A,by way of pipe 15, is conducted through the condenser and thence throughthe doubler in the manner specilied, and from there it is conducted intothe upper endof the distilling column 19, by the bypass 18, whence itflows downwardly from chamber to chamber, for the purpose and in themanner to be hereinafter more fully described. After the apparatus hasbeen fully started and is under operation, the valve 18 is shut oil, andthe cooling fluid is allowed to be discharged through the waste pipe 17,and under these conditions it is onlyuscd for cooling; the tubes 3 and 4of the condenser A and doubler ll. In starting the apparatus, however,this fluid is al-' lowed to pass down the pipe 18 through the valve 18'into the upper end of the distilling column 19.

The distilling column 19 is preferably inclined and provided withhorizon ally disposed partitions 22 forming a series of chambers. Thesechambersare connected by a series of exteriorly arranged pipes 23, thein let ends 24 of said pipes being vated above the level of thepartitions 22 and mounted in cross-bars or blocks 25,

which bars or blocks establish the liquid level in each chamber. Thelower or outlet ends 26 of the pipe 23 are on the same level with thepartitions 22, for the purpose to be hereinafter more fully described,this same arrangement being carried out through the length of thedistilling column 1.9 from chamber to chamber, forming a continuousdown-pipe arrangement for the downwardly flowing liquid. Thesedown-pipes 23 are furnished with 4-way fittings 23, which not onlyprovide the proper connections for the entrance and exit sections of thedown-pipes 23, but also form a simple and ready means of cleaning thesepipes by removing the screw plugs in the fittings 23'.

fDisposed below the distilling column 19 o distilling column 27,COTITPTlSlIL, section D, said column 27 being connecte to column 19 by aseries of pipes 2?,through which the liquid flows from the column 19into the column 27, passing through said column in the manner as abovedescribed for column 19, and finally reaching the lower end of column2?, where it is discharged by a series of pipes 28 into the heatingchamber 29 formed by a partition 30 arranged within a housing 31, andcomprising the section E, hereinbefore referred to as thebeer heater.

section C is another similarly constructed slightly eleiii - the pipe 33to flow over the Ell Ell

till

To the heating chamber 29, steam is admitted at 32, whereby thedownwardly flowing liquid is raised to the suflicient tem erature forvaporizing the same. As the liquid continues to fill chamber 29 it willeventually pass out of said chamber through the inverted U-shaped pipe33, mounted in the partition 30, into the chamber 34 inclosing a scrimoi tubes 35, the ends of said tubes being connected by header sections3.6 and 87, said hesder sections in "turn being supported within thechamber 34 by cross-partitions 38 and 39. In addition to thecross-partitions 38 and 39, the intermediate portions or the tubes aresupported by cross-partitions 40 and 41. .These partitions 38, 39, 40and 41 are so constructed as to permit the heated liquid coming from thechamber 29 through artition 38, under the partition 41, over 1; epartition 40, under the partition 39, and fins 1 discharge through thepipe 42, as the liqui rises suliiciently within the chamber 34 to thelevel of the discharge end of the outlet pipe 42. As this liquid flowsin and around the tubes 35, during its passage through the chamber 34,said tubes will be'heated, so that, as the alcohell-containing substanceor liquid enters said tubes, by way of the pipe 43, said alcoholicliquidwill be likewise heated. This alcoholic liquid or beer is notadmitted to the tubes until hot water or similar fluid begins to flowout of pipe 42, which will indicate that the apparatus is ready and inproper condition to start the distilling operation.

As the beer or alcoholic liquid is heated in the tubes 35, it is causedto rise and flow upwardly through the pipe 44 into the upper end of thedistilling column 27 by way of branch pipes 45, and also, if desired,into the lower end of distilling column 19 by branch pipes 46. Thecorrect point of entrance, however, must be decided according tocircumstances and experiene. From the points pi? admission, the beerflows downwardly in the manner above described for water, displaces thewater, and is dealcoholized in its downwardpassage, and finally leavesthe still by the pipe 42. to be understood that as the downcoming liquidthrough the distilling columns 19 and E27 enters the heating chamber 29by the pipes 28, the same is heated to a boiling tem-.

pcrature, the vapor fromi which rises through the distilling columns 27and 19 from chamber to chamber, heating the water in each chamber as itrises. This vapor at first is; merely water vapor, but u on the startingof theapparatus and the a mission of the beer by way of pipe 44 andbranch pipes 45 and 46 to the distilling columns 27 and 19,respectively, the beer will flow downwardly, displacing the water, thedistillation r thereof will begin, and the vapors eventually rising willbe alcohlic vapors.

It is' Th permit the rising of the vapors from chamber to chamber, eachof the partitions 22 is provided with a series of openings 47, overwhich is laced a strip or bar 48, preferably of wood and provided withvertically dis osed holes or openings 49, registering wit and forming acontinuation of the holes 47 in each horizontal partition 22. The bar 48is also provided with transverse, horizontally dis oscd openings 561?,whereby the liquid in eacli chamber may bepermittcd to flow each side ofsaid bar 48.. Above the bar 48 is placed an inverted trough or cap 51,known as a va r cap, which vapor cap is slightly spaced mm the bar 48,the lower side edges of said vapor cap being. preferably serrated andextending below the top edge of the partly inclosed bar 48, in whichposition said lower ed es of the vapor cap will be below the liquiclevel in said chamber, whereby a liquid seal will be provided, sothat-the vapors rising from chamber to chamber and passing upwardlythrough the openings 47 and 40 of the partition and bar, respectively,will be deflected downwardly by the inner vertical sides of the vaporcap 51, and in escaping will be forced to bubble upwardly through theliquid covering the patltion; 22. The bdttom edges of both verticalsides of the vapor cap 51 are notched or serrated, as shown at 52, thepurpose and ellcct of the notching being to divide the flow of vaporinto numerous small streams. The alcohol contained in the liquidcovering the partitions 22 of the various chambers is of lower boilingpoint than the temperature of the vapor rising from the heating chamber29, and the passage of the vapor through the liquid under the verticalsides of the vapor cap 51] causes a portion of the alcohol in the liquidto vaporize, so that the vapor increases and the liquid decreases inalcoholic content. The vapor rises and passes from chamber to chamberinthe manner desc ibed and by the time it has reached the point of.entrance for the beer at the branch pipes 45 and 46, it has beenconsiderably reduced in temperature and considerably enriched inalcoholic vapors. After passing the point of entrance of the beer by wayof branch pipes 45 and 46, the vapor rising through the alcohol and thetemperature difference between the vapor and the liquid will be slight,so that water vapors will be condensed by the passage of-thc vaporthrough the liq uid and the alcoholic content of thcyapors .willlief-increased bythe removal of the water, the alcoholic vapors of lowboiling point not being condensed to the same extcnt as the watervapors. The water resulting from this condensation flows down ward lythrough pipes 23 and eventually leaves the still through pipe 42. Thealcoholic vapors leaving the uppermost chamber of the distilling column19 pass through pipes 20 and enter the doubler section 13, assin throu htubes a 35 cs 21 and into P a g a 1 condensate carrying with it aportion of al- 10 cohol, also condensed, flows downwardly through pipes20, hack into the distilling column 19, where the alcohol isrte-vaporized and returned to the doubler B, While the Water continuesdownward andv eventually leaves the still by pipe 42. The tubes 3 in thecondenser A are kept at a temperature which Willcondense the vapors ascompletely as possible. The condensate, which is alcohol of more or lesshigh proof, leaves the still by pipe and thence to receiving tanksprovided for the purpose. The prosi'of the alcohol is due to thetemperature maintained in tubes 4. If the temperature be low, the resultwill be a high proof condensate from pipe 53. If the temperature behigh, the proof of the condensate Will be low. Pipes 20, 27 and 28 arethe only elements in the apparatus which are common to the ascendingvapor and the descending liquid, as elsewhere the course of the vapor isentirely separate from that of the liquid and the operation of theapparatus is continuous;

As hcreinbeforc stated, by inclining the main distilling columns 19 and2?, a greater horizontal area of the various chambers is obtained thanwould be possible with distilling columns of the same cross-sectionverticaliy disposed, giving a greater capacity in proportion to itscross-section, which capacity, to a great extent, governs the bubbling;area of the vapor caps, all of which advantages will be perfectlyobvious to one skilled in the art.

Another great advantage in incliningthese main distilling columns isthat the upper sides'thereof can he very conveniently made removable,either in whole or in part, Whereby instant access ma be had to theinterior of the still without disturbing. any other part of thedistillingcolurnn, if at any time it should become necessary for thepurpose of inspection or repairs.

It will also he apparent that, the construction and arrangement of thedown-pipes 23, vvith particular reference to-thc 4-way fittings 23, makeit an exceedingly simple and expeditious operation to clean out said,pipes, and also the various chambers connected thereby, by removing thedesired screw plugs in the couplings or fittings 23", and there afterproperly directing into said downpipes the cleaning fluid, such as steamor the like, according to Whether it is deisred to clean the chambers orsimply the pipe sectrons, l

. accuser in the same manner as the inlet and outlet ends of? thedown-pipes In both arrangement of pipes, the fluid is admitted to therespective chambers at a point approx-- imately' level with the bottomof said. chamhere, which will prevent the vapor rising"v from chamber tochamber frompassing through said pipe What We claim is:

1; In a continuously operatingstill, a distiliing column inclined at anangle between the perpendicular and horizontal and comprising a seriesof successively communicate mg chambers for the downward flow of liquidtherethrough, each of said chambers having a horizontally disposed floorto provide an extensive bubbling surface, each floor having a cappedopening for the up Ward fiou of vapor through the successive chambers,and means for maintaining liquid at a level in each chamber to etl'ectnorreally a seal for capped iioor openingi 2. In a continuously peratingstill, a dis. tilhng column inclined at an angle between theperpendicular and horizontal and comprising a series of successivelycommunicat ing chambers for the downward flow of liquid therethrough,each of said chambers having a horizontally disposed floor to proride anextensive bubbling surface, each floorhaving' a plurality of cappedopenings for the upward flow of vapor through the successive chambers,and means for mainraining liquid a level in each chamber to efiectnormally a' seal for the capped floor-openings.

3. in a continuously operating still, a distilling column inclined atan. angle between the perpendicular and horizontal and com prising atrunk. and a series of spaced. partitions extending horizontally acrossthe trunk to form therein successive charnhers, each partitionformingthe floor of an. up" per chamber and the ceiling of the adjacent lowerchamber and each partition having a plurality of capped openings for theupward flow ct vapor through the trunk, and means for maintaining"liquid in each chem.- her at a level to effect normally a seal.v for thecapped floor-openings.

4. in a continuously operating still, a distilling column'inclined atan. angle between the perpendicular and horizontal and comprising atrunk and a series of spaced pan titions extending horizontally acrossthe trunk to form therein successive chambers, each partition forming"the floor of an upper chamber and the ceiling ofthe adjacent ills ward

means apart from the-capped openings for through the successive chamberslower chamber and each partition having a plurahgy of capped openingsfor the up ow of vapor through the trunk,

forming communication between successive chambers to permit downwardflow of liquid through the trunk, and meansjor maintaining the liquid ineach chamber at a level to effect normally a seal for the cappedfloor-openings of said chamber.

5. In a continuously operated still, the combination of a heater for theliquid to be treated and a condenser placed above the heater, with adistilling column interposed between and communicating at its respectiveends with the heater and the condenser, said column being inclined at anangle between the perpendicular and horizontal and comprising a seriesof successsively communicating chambers for the downward flow of liquidtherethrough to the heater, the floors of the successive chambers beinghorizontally arranged to provide an extensive bubblin surface and eachof said floors having a p urality of capped openings for the upward flowof vapor through the successive chambers to the condenser, and means formaintaining the liquid in each chamber at a level to eflect normally aseal for the capped floor openings ofthe chamber.

6..In a continuously operated still, the combination of a heater for theliquid to be treated and a condenser placedabove the heater, with adistilling co umn interposed between and communicating at its respectiveends with the heater and the condenser, said column being inclined at anangle between the perpendicular and horizontal and comprising a seriesof successively communicating chambers for the downward flow of lit uidtherethrough to the heater, the floors o the successive chambers beinghorizontally arranged to provide an extensive bubbling surface and eachof said floors having a plurality of capped openings for the upward flowof vapor to the condenser,-means for maintaining the liquid in eachchamber at a level to effect normally a seal for the cappedfloor-openings of the chamber, and a separate pipe for conveying heatedfluid from the heater into the upper part of the distilling column toflow downiwardl through the successive chambers 7 n a continuouslyoperatin still, the combination of a heater for the liquid to be treatedand a condenser placed directly} above the heater, with u per and lowerdistilling columns relativey inclined and interposed between the heaterand condenser, said columns communicatmg with each other andrespectively with the heater and condenser. v

8. In a continuously operating still, the

combination of a heater for'the liquid to be treated and a condenserplaced directly above the heater, with upper and lower distillingcolumns relatively inclined and in-' terposed betweenthe heaterand'condenser, said columns communicating with each other andrespectively with the heater and condenser, and a separate pipe forconveyin r heated fluid from the heater to either co umn 9. Inacontinuously operating still, the

combination of a heater for the liquid to be treated and a condenserplaced directly combination of a heater for the liquidto be treated anda condenser placed directly above the heater, with upper and lowerdistilling columns relatively inclined and interposed between the heaterand condenmr, said columns communicatin with each other and respectivelywith t e heater and condenser,.both of said columns comprising a seriesof successively commumcating chambers for the downward flow of liquidtherethrough to the heater, the floors of the successive chambers beinghorizontally ar ranged and provided with capped openings for the upwardflow of vapor through both columns to the condenser, and means formaintaining the liquid in each chamber of both columns at a level toefi'ectnormally a seal for the capped floor-openings of the chamber.

1].. In a continuously operating still, the

combination of a heater for the liquid to be treated and a condenserplaced directly above the heater, with upper and lower distillingcolumns relatively inclinedand interposed between the heater andcondenser, said columns communicating with each other and respectivelywith the heater and condenser, both of said columns compris ng a for thecapped floor-openings of the chamleer, and a separate pipe for" conveyinheated fluid from the heater to either co umn. i x I 12. In acontinuously operatingystill, the

combination of a heater for the liquid to be treated and a condenserplaced directly above the heater, with upper and lower distillin columnsrelatively inclined and iuten pose between the heater and condenser,said columns communicating with each other and respectively with theheater and condenser, both of said columns comprising a series ofsuccessively communicating chambers for l the downward flow of liquid,therethrough.

to the heater, the floors of the successive chambers being horizontallyarranged and provided with capped openings for the upward flow of vaporthrough both columns to the condenser, means for maintaining the liquidin each chamber of both columns at a level to effect normally a seal forthe capped floor-openings of'the chamber, and a separate pipe forconveying heated fluid I 2 from the heater into the upper part of theeach of said chambers having a horizontally disposed floor to provide anextensive bub bling surface and each floor having a pluralit of cappedopenings for the upward flow of l'vapor through the successive chambersto .the condenser, and means for maintaining liquid at a level in eachchamber to effect normally a seal for the "capped fiooropenings,

14. In a continuously operated still, the

- combination of a heater for the liquid to be' treated and a condenserplaced above the heater, with upper and lower distilling columnsrelatively inclined and interposed between the heater and the condenser,said columns communicating with each other and respectivelycommunicating with the heater and condenser, both columns comprising a 5series of successively communicating chamhers for the downward flow ofliquid to the heater, each of said chambers having a horizontallydisposed fioor provided with a plurality of capped openings for the uward flow of vapor through the successive co um'ns to the condenser, andmeans for maintaining liquid at a level in each chamber to effectnormally-a seal for the capped floor-openl In a continuously operatedstill, the combination of a heater forthe liquid to be treated and acondenser placed above the heater with upper and lower distillingcolumns relativelv inclined andinterposed between the heater and thecondenser, said colheated fluid from the heater to the upper eeaasi Aumns'cpmm'unicating with'eao lather and res ectively communicating witthe heater an condenser, both columns cllmpiising a series ofsuccessively communicating'chambers for the downward flow of ii uid tothe heater, each of said chambers having a horizontally disposed floorprovided with a plurality of capped openings for'the upward How of vaporthrough the successive columns to, the condenser, means for maintainingliquid at a level in each chamber to offeet normally a seal for thecapped flooropenings, and a separate pipe for conveyiu, heated fluidfrom the heater to either col nmn. 16. In a continuously operated still,the combination or a heater for the liquid to be treated and a condenserplaced above the heater, with upper and lower distilling columnsrelatively inclined and interposed between the heater and the condenser,said columns communicating with each other and respectivelycommunicating with the heater and condenser, both columns comprising aseries of successively communicating chamhers for the downward flow ofliquid to the heater, each of said chambers having a horizontallydisposed floor provided with a pin rality of capped openings for theupward flow of vapor through the successive columns to the condenser,means for maintaiulug liquid at a level in each chamber to etfeetnormally a seal'for the capped floor openings, and a separate pipe forconveying part of the lower column and to the lower part of the uppercolumn.-

17. In a continuously operating still, a. distilling column inclined atan angle between the perpendicular and horizontal and comprising aseries of chambers witli'each having a horizontal floor and with eachchamber having a liquid inlet and a liquid outlet at a higher level thanthe inlet to .maintain at a predetermined level the liqno uid flowingthrough the chamber, an cute. riorpipe formin'g a communicationbetweenthe outlet of each chamber with the adjacent lower chamber, andthe horizontal door of each chamber having a pluralit of capped openingsfor the flow of vapor t erethrough from the adjacent lower chamber, saidopenings being normally sealed'by the liquid-level maintained in thechamber to offeet a bubbling action as the vapor passes throu -h saidopenings. 18. n a continuously operating still, a distilling wlumninclined at an angle between the perpendicular and horizontal andcomprising a series of successively communicating chambers for thedownward flow of liquid therethrough, means for maintaining the liquidat a, predetermined level in each chamber, each of said chambers havinga horizontal floor provided with a series 23m in bay bsiaw, a i" :fixe.on nine floor wiah a Wmfiiy eztezndi gggenings regisbsiing with fihes 0fand. mad hm having im'amvzawi s passages adjacam; the 530w fer fQQWhijilifli fmm 011a aide 01

